If it’s descending head-first down a tree trunk it’s probably a nuthatch! These small birds are easily recognized by this characteristic down hill descent. White-breasted Nuthatches will arch their bodies and point their beaks straight out in a territorial display of aggression to defend their food sources. There was a Hairy Woodpecker eyeing the suet feeder that this White-breasted Nuthatch at Sax-Zim Bog had just finished pecking at. A bit of suet is still clinging to its beak as it struck its pose, perhaps in an effort to deter the Hairy from coming to the feeder. Right after I took this shot, the Nuthatch disappeared to the back side of the tree trunk and I didn’t see it again. I also didn’t see the Hairy Woodpecker after that. I guess its display worked, at least for the next few minutes.